This invention pertains to the art of material handling apparatus and more particularly to workpiece guiding and feeding apparatus.
The invention is particularly applicable to consecutively feeding workpieces to a thrufeed type centerless grinder for processing therethrough. However, it will be appreciated by those skilled in the art that the invention may be readily adapted to use in other types of equipment and environments.
Centerless grinding is a method of grinding a cylindrical surface without mechanically rotating the workpiece between fixed centers. The workpiece is supported and rotates between three fundamental machine components, namely, a grinding wheel, a regulating or feed wheel and a work rest. The grinding wheel does the actual grinding while the work rest positions the work for such grinding. The regulating wheel has the three-fold function of controlling the speed of workpiece rotation, controlling sizing of the workpiece and controlling the rate of work travel through the thrufeed type grinding machine. Moreover, and in thrufeed grinding, the actual grinding is performed by passing the workpiece axially between the grinding and regulating wheels. The speed, diameter and angle of inclination of the regulating wheel determines the workpiece traverse rate.
In some centerless grinding installations, workpieces are consecutively fed to the grinder work rest from a workpiece supply or reservoir by means of conveyors, workpiece slides and the like. Such workpiece handling apparatus must thus be precisely positioned between the supply and work rest. However, in centerless grinding operations, the grinding wheel contour is slowly changed from one size to another so that the accuracy with which the parts may be ground is affected. Therefore, the grinding wheel must be dressed or trued at regular intervals. Each dressing or truing operation reduces the grinding wheel diameter. Thus, in order to retain the proper dimensional relationships between the grinding wheel, work rest and regulating wheel, it is necessary to periodically adjust the work rest and regulating wheel generally laterally toward the grinding wheel face following each truing operation. Furthermore, and as each worn grinding wheel is replaced with a new one, it is necessary to adjust the work rest and regulating wheel laterally away from the new grinding wheel to again establish proper spacial orientation therebetween.
In prior apparatus for sequentially feeding workpieces into a thrufeed type centerless grinder, it has been necessary to correspondingly adjust the feed apparatus with each adjustment of the work rest and regulating wheel. While the amount of each adjustment may only be on the order of magnitude of a few thousandths of an inch, prior devices have not provided or incorporated any means for automatically effecting the necessary feed structure adjustment. As a result, it has heretofore been necessary to physically move or adjust the feed apparatus independently of work rest and regulating wheel adjustments. Since the feed apparatus may itself be receiving workpieces from a bulk type workpiece reservoir or from another centerless grinder, the movement and readjustment required therefor was oftentimes exceedingly tedious and time consuming. In some instances, it has also been necessary to move and adjust the bulk feeders themselves. As a result, natural grinding wheel wear and periodic dressing or truing caused substantial grinder downtime because of the additional time required for repositioning and readjusting the attendant workpiece feeding equipment. Such downtime, in turn, causes a reduction in overall production output.
Further, vibratory structures or conveyors have not heretofore been effectively usable in the type of grinding operations here involved. Such vibratory structures are, by their very nature, extremely heavy and rather bulky. Thus, adjustments of such structures at regular intervals is even more difficult and time consuming. In addition, no means has previously been developed to prevent transference of vibrations from the vibratory structure to the grinder work rest. Vibrations which are so transferred cause undesirable "chatter" in the overall grinding operation.
It has, therefore, been desired to develop some means which would facilitate automatic adjustment of workpiece feeding equipment associated with centerless grinders in order that separate readjustment thereof at regular intervals may be substantially reduced and/or entirely eliminated. It has been additionally desired to provide such means which would also reduce and/or entirely eliminate the necessity for moving attendant workpiece feed or supply such as bulk workpiece reservoirs and the like each time the grinder work rest and regulating wheel were adjusted relative to the grinding wheel. It has also been desirable to provide a feed or guide mechanism which could advantageously utilize the benefits obtainable from vibratory type structures or conveyors while at the same time eliminating the undesirable aspects thereof.
The present invention contemplates new and improved apparatus which overcomes all of the above referred to problems and others and provides an adjustable feed or guide mechanism for feeding workpieces to a centerless grinder. The invention features structure which is simple in design and construction, is economical to use, is automatically adjustable responsive to adjustment of an associated work rest, accommodates the effective use of vibratory type structures or conveyors, is adapted to be used intermediate a bulk workpiece feeder and a grinder or between a pair of consecutive grinders, and is readily adapted to use in many other environments and applications.